Decorative, thermoformable films are widely used to form three-dimensional, decorative accessories and panels that can be attached to a wide variety of industrial and consumer items such as motor vehicles, boats, furniture, building materials, appliances, and the like. For instance, metallized polymeric films have been used to fabricate three-dimensional objects that look as if they are made from metal. Substitution of these objects for their metal counterparts can result in at least one of the following: lighter weight, lower manufacturing costs, better weather resistance, and sharper detail.
Fabricating three-dimensional objects with surfaces that look metallic is only one of many possible applications for decorative, thermoformable films. Many different surface effects can be incorporated into a thermoformable film, and these decorative films can be used in a wide variety of applications. For example, decorative films can also be used to provide surfaces that appear, for example, to be painted or colored, to be fluorescent or phosphorescent, or to be mirror-like or retroreflective. The surfaces can also look like wood, stone or other ceramic, parchment or other paper, or leather or other textile fabrics. The surfaces can be decorated with one or more graphic images or patterns. WO 88/07416 and U.S. Pat. No. 6,083,335 describe thermoformable films that have surfaces that appear as high gloss painted surfaces for use in the automotive industry. U.S. Pat. No. 6,071,621 describes metallized polymeric films that can be used to make a wide variety of articles for automotive, furniture, and other uses.
In a conventional thermoforming process, thermoformable film is formed into a three-dimensional shaped film and then reinforced by backfilling with a curable fluid (e.g., a polymeric material) that hardens to form a supporting body. To improve the strength of the bond between the film and the reinforcement, it is common for the film to have a primer layer (also referred to as a tie layer). Many kinds of conventional primer layer compositions are known. Representative examples of conventional primer layer compositions include (1) a polyamide such as the materials described in EP 0,392,847 B1; (2) a hydroxy functional polymer such as a hydroxy functional polyurethane or vinyl resin (e.g., VAGH copolymer available from Dow Chemical); (3) a carboxyl functional polymer such as VMCH available from Dow Chemical; (4) an amine functional polymer; or combinations thereof.